In some printed wiring boards, mesh fibers composed of warp fibers and weft fibers are embedded for suppressing extension and contraction due to temperature and humidity and for reinforcing strength. As the fibers to be embedded in the printed wiring boards, glass fibers are typically used.
In recent years, wiring on the printed wiring board has become denser, and the signals which are transmitted by the wiring have become higher-frequency signals. In accordance with this, higher characteristics have been required of printed wiring boards. When the characteristics of the printed wiring boards are to be further enhanced, the relation of the direction of the embedded fibers and the direction of the wiring becomes a problem, and it is known that the characteristics are more enhanced when these directions are slightly shifted from each other than when these directions correspond to each other. On printed wiring boards, wirings are generally printed parallel with one side of the printed wiring boards. Therefore, when such a printed wiring board having the directions of fibers and wirings shifted from each other is cut out from the sheet material with the fibers being embedded, which becomes a basis for cutting the printed wiring board, the printed wiring board is cut out so that the sides are formed, which are oblique with respect to the direction of extension of the fibers in the sheet material.
However, even if the printed wiring board which is completed by being cut out from the sheet material is observed, the orientation of the fibers may not be easily known because the fibers are embedded inside, and an opaque solder resist coating film for protection is formed on the printed wiring board surface.
Meanwhile, in order to guarantee the performance of printed wiring board which is completed, confirming the orientation of the embedded fibers is one of the important items.
Here, in order that a plating solution hardly penetrate to the wiring along the fibers embedded in the printed wiring board from the through-holes provided in the printed wiring board, it is proposed to make the direction of the embedded fibers and the direction of the wiring differ from each other.    Patent document 1: Japanese Laid-open Patent Publication No. S61-42992.    Patent document 2: Japanese Laid-open Patent Publication No. S61-47844.